Seven low-intensity bombs exploded across the Indian IT city of Bangalore on Friday, killing one person and wounding at least 15, police said.
"In all these cases they have created the blast using timer devices," Bangalore Commissioner of Police Shankar Bidri told reporters at the site of one of the blasts. "Explosives have also been used, in quantity equal to one or two grenades."
Bangalore hosts the bulk of India's IT and outsourcing business and is home to more than 1,500 top firms, including offices of large global firms such as Microsoft , Intel and IBM .
M. R. Pujar, additional police commissioner for Bangalore said "crude explosives" had been used.
"There were seven low-intensity explosions," he told Reuters. "Some of them were in crowded areas. At least person was killed and 15 to 20 were injured."
Local TV showed one small shopping stall in Bangalore with broken windows and its concrete floors broken in pieces.
Rubble littered another site.
India has suffered a wave of bombings in recent years, with targets ranging from mosques and Hindu temples to trains.
But it is unusual for any group to claim responsibility for attacks.
Islamist militant groups in Pakistan and Bangladesh intent on fanning hatred between Muslims and Hindus in India, and damaging a fragile peace process between New Delhi and Islamabad, are often blamed for bomb attacks in India.
In May eight bombs, many strapped to bicycles, ripped through a crowded shopping area in the western city of Jaipur, killing 61 people and injuring hundreds more.
Police said that attack bore some hallmarks of the Bangladeshi militant group Harkat-ul-Jihad al Islami (HuJI).
Indian shares extended losses to more than 3.5 percent on Friday after reports of blasts in the southern city of Bangalore, home to top outsourcers Infosys Technologies and Wipro.